Novel zinc(II)−curcumin molecular probes bearing berberine and jatrorrhizine derivatives as potential mitochondria-targeting anti-neoplastic drugs

Berberine and jatrorrhizine are major bioactive components that are emerging as potential anti-cancer drugs. However, no zinc(II) – berberine/jatrorrhizine – curcumin compounds have been reported in the literature to date. Therefore, the molecular mechanisms associated with their cytotoxicity remain unexplored. To investigate the potential mitochondria-targeting ability, anti-neoplastic activity, and utility in cell imaging of berberine and jatrorrhizine derivates, four novel zinc(II) complexes, [Zn(Ber)(H2O)Cl2] (Zn(Ber)), [Zn(Ber)(Cur)Cl] (Zn(CurBer)), [Zn(Jat)(H2O)Cl2] (Zn(Jat)), and [Zn(Jat)(Cur)Cl] (Zn(CurJat)) bearing the berberine-derived ligand 2,2,2-trifluoroacetate 10-methoxy-9-((9-((2-(pyridin-2-yl)ethyl)amino)nonyl)oxy) −5,6-dihydro- [1,3]dioxolo[4,5-g]isoquinolino [(Torre et al., 2015; de Ruijter et al., 2020) 3,23,2-a]isoquinolin-7-ium (Ber), the jatrorrhizine-derived ligand 2,2,2-trifluoroacetate 2,9,10-trimethoxy-3-((9- ((2-(pyridin-2-yl)ethyl)amino)nonyl)oxy)-5,6-dihydroisoquinolino [(Torre et al., 2015; de Ruijter et al., 2020) 3,23,2-a]isoquinolin-7-ium (Jat), and/or curcumin (H-Cur) were first synthesised in this study. Zn(Ber), Zn(CurBer), Zn(Jat), and Zn(CurJat) showed higher cytotoxicity against human MCF-7 (breast adenocarcinoma) cells than did cisplatin, with IC50 values ranging from 0.21 to 4.45 μM. The anti-neoplastic activities of the zinc(II) – berberine/jatrorrhizine – curcumin complexes were in the following order: Zn(CurBer) > Zn(CurJat) > Zn(Ber) > Zn(Jat) > cisplatin > H-Cur > Ber > Jat > ZnCl2. Among these, Zn(CurBer) displayed the highest cytotoxicity (0.21 ± 0.06 μM). Furthermore, mechanistic investigations revealed that Zn(CurBer) and Zn(CurJat) could accumulate in the mitochondria, exhibit red fluorescence, and trigger mitophagy and apoptosis. In vivo anti-cancer evaluations also suggested that Zn(CurBer) inhibited MCF-7 xenograft tumour growth more effectively than cisplatin and Zn(CurJat). This is the first report describing the synthesis of zinc(II) – berberine/jatrorrhizine – curcumin complexes and their potential use as molecular probes and mitochondria-targeting anti-neoplastic drugs.